Bruce A. Schulte

Chemical ecology of marine organisms: An overview

An overview of marine chemical ecology is presented. Emphasis is placed on antipredation, invertebrate-toxic host relationships, antifouling, competition for space, species dominance, and the chemistry of ecological interactions.

Signal–receiver interplay in the communication of male condition by Asian elephants

Signal design and meaning are dependent on the condition of the sender and receiver as well as the response of the receiver. This study examined (1) whether female Asian elephants, Elephas maximus, can distinguish between a conspecific male in musth and nonmusth states using urinary signals, (2) how the oestrous condition of the female affects discrimination, and (3) correlation of female responses with the testosterone level of the male. Musth is a rut-like state displayed by healthy adult male elephants. Males in musth dominate nonmusth males and may be preferred by females as mates. Urine was collected from two captive male Asian elephants during nonmusth periods and from one of these males during times of musth. Samples of musth and nonmusth urine and control liquids were placed in an elephant enclosure weekly for 16 weeks, the length of a female oestrous cycle. Primary response behaviours were approach and four trunk-tip motions, namely sniff, check, place and flehmen. Musth urine consistently elicited greater responses than nonmusth and control samples. Females were more responsive during their follicular (sexually receptive) than luteal (unreceptive) stages of oestrus. Furthermore, females appeared to be sensitive to the degree of musth as responses increased with rising serum testosterone levels of the male donor. Chemical signals from males are a likely source of honest signals related to status and reproductive condition. Female elephants appear capable of detecting differences in a male based upon urinary chemosignals. Copyright 1999 The Association for the Study of Animal Behaviour.

Insect Pheromones and Precursors in Female African Elephant Urine

Using automated solid-phase dynamic extraction and gas chromatography–mass spectrometry, our search for urinary chemical signals from ovulatory female African elephants (Loxodonta africana) has revealed the bark beetle aggregation pheromones frontalin, exo-brevicomin, and endo-brevicomin, as well as their precursors and the aphid alarm pheromones (E,E)-α-farnesene and (E)-β-farnesene. Enantiomeric ratios for brevicomins have been determined. Prior discovery of common insect/elephant pheromones in Asian elephants, namely, (Z)-7-dodecenyl acetate and frontalin, suggests that the present findings may yield valuable insights into chemical communication among African elephants.

Male African elephants, Loxodonta africana, can distinguish oestrous status via urinary signals

African elephants are a polygynous species that raise offspring in a matriarchal society. Unlike females, males disperse, spend time in male groups and search for mates when mature. Urinary chemical signals aid males in detecting reproductively active females. A preovulatory pheromone has been identified in Asian elephants, Elephas maximus, but has not yet been experimentally identified in African elephants. In this study, the goal was to determine whether adult captive male African elephants can distinguish between urine from conspecific females in luteal and periovulatory oestrous stages as an indication that a preovulatory pheromone is released in the urine. Urine was collected from seven different female African elephants during their luteal and periovulatory periods of oestrus. Bioassays were conducted with nine adult male elephants housed at six different facilities. Males were presented with the two urine types and a control sample once a day over 3 days to reduce sample novelty, which can result in misleadingly high responses. All males showed greater chemosensory responses to the periovulatory urine by trial 3 with the ability to distinguish the urines increasing over the 3 days. This is the first experimental behavioural evidence that African elephants release an oestrous pheromone in the urine. The ability of the captive male elephants to discern between the two urine types bolsters the hypothesis that there is a preovulatory pheromone in African elephants and encourages efforts to identify it.

Scent marking and responses to male castor fluid by beavers

Stable URL:http://links.jstor.org/sici?sici=0022-2372%28199802%2979%3A1%3C191%3ASMARTM%3E2.0.CO%3B2-QJournal of Mammalogy is currently published by American Society of Mammalogists.Your use of the JSTOR archive indicates your acceptance of JSTORs Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTORs Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/asm.html.Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.The JSTOR Archive is a trusted digital repository providing for long-term preservation and access to leading academicjournals and scholarly literature from around the world. The Archive is supported by libraries, scholarly societies, publishers,and foundations. It is an initiative of JSTOR, a not-for-profit organization with a mission to help the scholarly community takeadvantage of advances in technology. For more information regarding JSTOR, please contact support@jstor.org.http://www.jstor.orgTue Dec 11 11:17:30 2007

Using anal gland secretion to determine sex in beaver

Controlling beaver (Castor canadensis) populations is a problematic issue for wildlife managers in North America. Management of beaver can be facilitated by determining sex ratio of a population, but this requires ready identification of gender for live and harvested beaver. We developed a technique using color and viscosity of anal gland secretion (AGS) to identify gender of beaver. Inexperienced volunteers inspected AGS from beaver in 3 regions of New York. Using AGS collected and stored in glass vials, 4 volunteers correctly identified sex of 24 beaver (16 M, 8 F) livetrapped during spring 1992; 2 additional pairs of volunteers correctly discriminated 45 beaver (21 M, 24 F) livetrapped in spring 1993 and 1994. Using fresh AGS viewed in the field, 1 volunteer correctly discerned 25 beaver (15 M, 10 F) caught in October 1993; and 2 volunteers distinguished sex of 5 beaver (3 M, 2 F) captured in November 1992 without error. Male AGS was Kraft brown (P55, Marker color system) to sepia (P56) and viscous (490-507 centipoise [cP] at 25.8 C and 60 rpm, Brookfield DV-11 + viscometer), while female secretion was pale to medium olive (P34, P39) or warm gray (P191), less viscous (4-28.7 cP, 23-25.4 C, 50 or 100 rpm) and flowed more (P < 0.001) than male AGS. Secretion color and viscosity were discriminating means of distinguishing the sexes in the field.

Musth, Sexual Selection, Testosterone, and Metabolites

Musth is an annual, yet asynchronous, rut-like condition that is experienced by many adult African and Asian male elephants. Behaviorally, musth is characterized by heightened aggression, decreased feeding, urine dribbling, temporal gland secretion and enhanced sexual activity. Musth improves the access of a male to reproductively active females through increased mobility and a higher dominance ranking (intrasexual competition). Whether females prefer males in musth as mates is as yet uncertain (intersexual choice). Females can distinguish among the odors of males in musth and nonmusth. Although behavioral musth has been associated with greatly elevated plasma testosterone levels, a recent study in Sri Lanka shows that intensified aggressiveness follows maximal testosterone secretion and proposes that behavioral musth is a consequence of declining androgen levels. Our data from an Asian male elephant in North America suggest that either declining or rising serum testosterone may be related to “musth behaviors.” Our report demonstrates that certain aspects of body physiology are greatly altered during musth. Rather than a single state, our data suggest that musth is an ever-changing condition with some typical stages. Specific chemical compounds released at different stages of musth may serve individually or in combination as honest signals of male condition.

Behavioral and Ecological Characteristics of A “Climax” Population of Beaver (Castor Canadensis)

We describe the characteristics of an unexploited (unharvested) beaver population in New York State. The results are based on data collected from 1984 to 1993. The following features differed from exploited (harvested) populations: Beavers colonized steeper stream gradients; Families contained a large percentage of 3-year-olds (young that stay one more year); Preferred tree species became depleted and beaver fed on less palatable species; and they extended their trails to more distant foraging areas. In other ways, our population resembled trapped populations: Densities of colonies per stream kilometer did not differ from those reported in other studies; Body weights did not differ from those in other studies; Family size was within the range of other populations; The numbers of scent mounds in territories are not reduced or increased; and The response to artificial scent marks does not differ in intensity from other areas. In conclusion, the beavers are adaptable and need little management by humans. Beaver management and control of beaver numbers are driven by conflicts with humans, and not by any needs of the beavers themselves.

Chemical Signals of Elephant Musth: Temporal Aspects of Microbially-Mediated Modifications

Mature male African (Loxodonta africana) and Asian (Elephas maximus) elephants exhibit periodic episodes of musth, a state in which serum androgens are elevated, food intake typically decreases, aggressiveness often increases, and breeding success is enhanced. Urine is a common source of chemical signals in a variety of mammals. Elephants in musth dribble urine almost continuously for lengthy periods, suggesting that the chemicals in their urine may reveal their physiological condition to conspecifics. We investigated the volatile urinary chemicals in captive male elephants using automated solid phase dynamic extraction (SPDE) and gas chromatography–mass spectrometry (GC-MS). We found higher levels of alkan-2-ones, alkan-2-ols, and some aromatic compounds in urine from males in musth than in urine from non-musth males or from females. Levels of ketones and alcohols increased as the urine aged, likely due to microbial metabolism of fatty acids. Protein-derived aromatic metabolites also increased in abundance after urination, likely due to microbial hydrolysis of hydrophilic conjugates. We suggest that microbes may play an important role in timed release of urinary semiochemicals during elephant musth.

Intrasexual chemical communication and social responses of captive female African elephants, Loxodonta africana

In matrilineal societies, competition between females can occur within and between social units. Dominance hierarchies reduce costly conflicts when reliable cues of status are available, and reproductive condition may alter individual or group status. Female African elephants live in matriarchal groups with linear dominance hierarchies occurring within and between groups; elephants use chemical signals to mediate social interactions. If reproductive condition has important implications for inter- or intragroup behaviour, then females should discriminate between chemical signal sources that reveal reproductive condition. We examined whether trunk-tip contacts between females within a social group were related to phase of oestrus. Observations were conducted on 21 reproductively viable females at nine zoological facilities in North America. Females in the follicular phase received contacts to the urogenital region at a higher rate than did luteal phase females, and contacts increased with approaching ovulation. This supports the existence of an oestrous signal. We also examined whether an oestrous signal was evident by female investigation of urine collected from the luteal and follicular phases of unfamiliar conspecifics. Elephants responded to unfamiliar urine more than to the control, but response rates to the urine types did not differ. Females within a social unit detected differences in oestrus, but they did not show such discrimination to urinary signals from unfamiliar females. Further evaluation of the existence of a female-to-female oestrous pheromone requires assessing responses to urine from familiar individuals. Understanding the relationship between oestrous condition and dominance status can shed light on the adaptive value of sociality.